What Is The Principle Of TFT-LCD Display?

• Backlight: The light source of the display, the backlight of the LCD is commonly used with two CCFL (cold cathode light tube) backlights and LED backlights.

CCFL has the advantages of high power, high brightness and low power consumption.

LED has the advantages of low power consumption, uniform light source, long life and small size. The price is slightly more expensive.

LED displays appearing on the market are actually "LED-backlit liquid crystal displays". Currently, the more popular liquid crystal displays are "CCFL-backlit liquid crystal displays." Both are just different backlights for LCDs. The latest technology is the OLED display.

• Liquid crystal: The liquid crystal used in TFT-LCD is TN type liquid crystal, and the liquid crystal molecules are elliptical.

a. Characteristics of liquid crystal: TN type liquid crystals are generally connected in series along the long axis direction, and the long axes are arranged in parallel with each other. When it comes into contact with the grooved surface, liquid crystal molecules are arranged in the groove in the direction of the groove.

b, vertical distribution of liquid crystal: when the liquid crystal is contained in the middle of two groove-like surfaces, and the directions of the grooves are perpendicular to each other, the arrangement of the liquid crystal molecules is such that the upper surface molecules are along the a direction; the lower surface molecules are along the b direction; The molecules on the upper and lower surfaces produce a rotation effect, so the liquid crystal molecules produce a 90 degree rotation between the two surfaces.

c. Light and liquid crystal molecules have a deflecting effect: it can be seen that a beam of light incident on the upper surface is arranged in the same direction as the groove, but the direction of the light beam is deflected by the rotation of the intermediate liquid crystal molecules, and finally from the lower surface When the light is emitted, the arrangement direction of the light rays becomes parallel to the direction of the groove of the lower surface.

d. The liquid crystal is evenly distributed under the action of voltage: when a voltage is applied between the upper and lower surfaces, the liquid crystal molecules are arranged along the direction of the electric field to form an upright arrangement. At this time, the incident light is not affected by the liquid crystal molecules, and is directly emitted from the lower surface.